Mobile devices have moved from simple voice communication to performing functions traditionally performed by larger devices such as laptops and desktop computers. Such functions include streaming multimedia content, enabling high definition online gaming, and the like. These functions have become an integral part of our daily lives, but each of these and other functions enabled by mobile devices multiplies the bandwidth required for each user. Therefore, wireless network designs have built-in intelligence to determine how, when, and whether to grant access to a given user or mobile device to connect with the network and begin communication. This intelligence is sometimes referred to as call admission control.
An example of a wireless broadband network which has such call admission control is Long-Term Evolution (LTE). LTE is an end-to-end broadband IP network that aims to provide high sector capacity, scalability, improved end-user throughputs, and reduced user plane latency, bringing significantly improved user experience with full mobility. However, the capacity of the LTE network is limited. Accordingly, mobile operators face a delicate balancing act in trying to manage the high speed data traffic desired by its users, and maintaining the subscriber's quality of experience by providing a selective session call admission control mechanism.
As per 3rd Generation Partnership Project (3GPP) standard [http://www.3gpp.org/ftp/Specs/archive/23_series/23.401/23401-8g0.zip], call admission control from the LTE network infrastructure point of view can be broadly and generally categorized as including the following three stages:                1. Initial random access admission control at the base station or evolved NodeB (eNB);        2. Mobile device or user equipment (UE) signaling session admission control at a mobility management entity (MME); and        3. Traffic session admission control at the eNB.        
Initial random access admission control is the first level of admission control where the base station or evolved NodeB (eNB) decides whether to initiate a communication path with a mobile device. Once this initial random access admission control is complete, the mobile devices can send the next set of signaling messages to the MME via the eNB, which performs the second stage UE signaling session admission control. Once the MME accepts UE signaling session admission control, then the eNB executes the traffic session admission control and finally decides whether to admit the UE to send and receive traffic.
An ineffectual traffic session grant during the initial random access admission control stage may lead to substantial signaling load processing for the second and third stages of the call admission control. This may result in bad QoS experienced by end-users and decrease the overall network performance by overwhelming the base station or eNB with UEs that cannot be admitted.
Accordingly, there exists a need for techniques for an improved initial random access admission control in wireless broadband networks such as LTE.